Wild animals deal with nature's harsh reality every day. Not only must such wild animals find sufficient food to sustain themselves, they must generally avoid predators. In order to adapt to these harsh realities, many wild animals have senses that are far more sensitive than human senses.
Many predators, in general, must chase, or otherwise stalk their prey. One common adaptation for such predators is the ability to perceive depth. Thus, many predators, such as coyotes and wolves have both eyes located on the front of their head in order to facilitate depth perception. Many predators are also keenly aware of depth by virtue of superior hearing. For example, unlike humans, many predators, such as dogs, wolves and coyotes have their ears facing somewhat forward thereby allowing the predators to resolve, at least to some degree, depth from sounds perceived ahead of them. Still another sense that is extremely powerful in some predators is the sense of smell. For example, dogs in general are believed to have a sense of smell that is in the range of one hundred thousand to a million times more sensitive than a human's. All of these senses and abilities combine to provide an innate ability of a predator to perceive and capture prey.
The senses and abilities described above also make the predator, such as a wolf or coyote, an extremely perceptive and cunning prey. In the hunting of such predatory wild animals, it is known to utilize a predator call that potentially mimics the sound of a bleating fawn, or some other natural prey of the sought predator. Additionally, effective predator calling is performed in such a way that the predator believes that it is closing in on some prey, and is not made skittish by some sense, characteristic or artifact either from the hunter, or the call, that is unexpected to the predator.
It is believed that there are three basic things that characterize a good call. First, the call must generate a good tone. Second, the call must facilitate the ability of the hunter generate good cadence, or basically the song or call of the prey. Finally, a good call must also facilitate the generation of proper call volume. In order for a caller to successfully lure a predator, all three factors must be maintained consistently together while the predator is lured.
Of the three factors listed above, volume is believed to be at least among the most important. Specifically, if the call is too loud the predator's inquisitiveness will not be maintained and the predator will not want to investigate the sound. Additionally, many predators have hearing that is so perceptive that based on the distance on the order of 100 to 200 yards, they can gauge their surroundings and the distance and relative position of the caller. If the volume is not consistent with what the predator expects, as far as stalking the pseudo prey, the predator will spook, and not be lured sufficiently close to be taken.
Most wild animal calls utilize a reed that generates a tone by vibrating against a reed bed in response to the hunter's breath. In order to adjust the tone of a call, the length of the reed must be adjusted, which is done by essentially moving the hunter's lips forward or aft on the reed bed. The position of the lips on the reed bed creates a pinch point which defines the portion of the reed that is allowed to resonate and produce the tone. In order for a predator to be successfully lured, predator calls are often relatively complex sounds intended to resemble that of other similar predators, a bleating fawn, or a bleating or distressed jackrabbit. Thus, within the duration of an individual bleat, the cadence and tone of the call may be varied to produce the desired call.